ELEMNT ACE Wind sensor and Wahoo Wind Dynamics

What is the wind sensor?

ELEMNT ACE features a wind sensor, a front-facing air pressure sensor which enables cyclists to measure the effects of relative air resistance in real time. When a cyclist is travelling faster than 3mph, ACE will calculate Air speed from the air pressure experienced by the wind sensor as a function of the bike's current speed and a variety of wind conditions (headwinds, tailwinds, or the effect of drafting behind another cyclist).

By comparing the Air speed against the bike’s speed data (sourced from GPS speed or an external speed sensor), the wind sensor can calculate a Wind Impact value, which shows the relative impact of a headwind, tailwind, or reduced wind resistance experienced from drafting another cyclist.

Air speed = Bike speed +/- Wind impact (headwind/tailwind/drafting benefit)

Air Speed will always be a positive number. Wind Impact will be a positive or negative number.

Example 1 -- Headwind
- You are riding at 20 mph. (Bike speed = 20 mph).
- There is a 5 mph headwind.
  - Air Speed = 20 + 5
  - Air Speed = 25 mph
  - Wind Impact = 20 - 25
  - Wind Impact = -5 mph
Example 2 -- Tailwind
- You are riding at 20 mph. (Bike speed = 20 mph).
- There is a 5 mph tailwind.
  - Air speed = 20 - 5
  - Air speed = 15 mph
  - Wind Impact = 20 - 15
  - Wind Impact = 5 mph
Example 3 -- Drafting
- You are riding at 20 mph. (Bike speed = 20 mph).
- You are drafting behind another rider. There is a 5 mph draft benefit.
  - Air speed = 20 - 5
  - Air speed = 15 mph
  - Wind Impact = 20 - 15
  - Wind Impact = 5 mph

Wind Impact zones -- AirBoost / Neutral Air / AirDrag

Using bike speed, Air Speed, and Wind Impact calculations, the ACE divides your ride into wind zones – time intervals spent with various wind conditions:

Air Drag

When bike speed is hindered by a headwind
Bike speed is < Air speed

Air Boost

When bike speed is aided by a tailwind or reduced air resistance from drafting behind another cyclist
Bike speed is > Air speed

Neutral Air

When there is little to no headwind, tailwind, or draft benefit or bike speed is too low or Air Speed is too close to Bike speed for the sensor to gather a reliable value
Bike speed is = Air Speed

During a ride, Wind Impact Zones are shown with colors (red for Air Drag, green for Air Boost, and white for Neutral Air) for immediate clarity in various data fields on the ACE. After a ride wind data is further analyzed by the Cloud and Air Drag and Air Boost zones are further divided into heavy and light sub-zones:

Heavy Air Drag (red)
Light Air Drag (orange)
Neutral Air (gray)
Light Air Boost (light green)
Heavy Air Boost (dark green)

Why should you care about wind data?

Just as a power meter captures your physical effort with far greater precision than subjective feel, the wind sensor provides objective insight into the environmental conditions you're riding through. Viewed alongside speed, grade, and power data, it gives you a clearer picture of how wind is affecting your performance, both during and after a ride.

Most importantly, Wind Impact zone color coding makes it immediately clear when to tuck into a more aerodynamic position while riding solo in the open, and how effective your draft is when following another rider. This is especially useful when deciding whether it’s worth the effort to burn a match to get back onto the wheel ahead.

Setting up your device

For the pressure sensor to gather the most accurate data, the computer should be mounted with its face as close to horizontal as possible, ideally within 5° of horizontal.

0–5°: Negligible impact on data accuracy.
5–10°: Data accuracy gradually degrades.
Beyond 10°: Air pressure and wind/drafting values cannot be considered accurate.

An easy way to check the angle of your computer is to place your phone on the surface of the ACE screen and use the native Measure app for iOS or the third party Bubble Level, Spirit Level app for Android.

In-ride experience

Data Fields

Wind sensor data can be added to the data pages of workout profiles through a variety of data fields, listed below. These can help to quantify and illustrate Wind Impact for glanceable, actionable feedback to inform training strategy.

Air Speed – Current air speed value (neutral background)
Potential Speed – The speed you would theoretically be riding at, if there were no impact from wind (neutral background)
Potential Speed (Zone Colored) – Potential speed with Wind Impact Zone expressed as one of five background colors (Dark green, light green, white, orange, red)
Total Time in Air Boost – Shows accumulated time in Air Boost (tailwind or draft benefit) conditions with a green background that fills from the bottom, dependent on the percentage of the ride in which you experienced Air Boost
Total Time in Air Drag – Shows accumulated time in Air Drag (headwind) conditions with a red background that fills from the bottom, dependent on the percentage of the ride in which you experienced Air Boost
Wahoo Wind Dynamics – shows a simple graphical representation of the relative time spent in each of the Wind Zone categories, excluding ‘neutral air’ – dark green, light green, orange, or red for heavy air boost, light air boost, light air drag, or heavy air drag, respectively
Wind Grade (Slope Background) – The impact of a headwind/tailwind/draft benefit, presented as a perceived grade, calculated from a force algorithm that accounts for current speed, wind impact, current grade, rolling resistance, and acceleration.
Wind Impact – The approximate effect of wind conditions on your speed (neutral background)
Wind Impact (Colored) – Wind impact value with one of three background colors (green, white, or red)

Wind metrics page

For the most detailed analysis of Wind Impact, ACE users have the option to view the Wind data page. This page provides a comprehensive view of your preferred wind metrics, illustrated with clear graphical visualizations, including:

A speedometer visualization which includes the current Bike Speed numerical value and a graphical representation of Wind Impact
Six customizable data fields which, by default, contain
1. Wind Impact
2. Wind Grade
3. 3 second Average Power
4. Heart rate
5. Total Air Boost
6. Total Air Drag
The Resistance Ratio visualization

When experiencing a headwind, the Wind Impact will display in red, with a negative sign to demonstrate the negative impact on your potential speed.

When experiencing a tailwind or draft benefit, the Wind Impact will display in green, with a positive sign to demonstrate the positive impact on your actual speed.

Your current Wind Impact value is also expressed at the bottom of this page as a Resistance Ratio, the ratio between the resistance caused by wind conditions, and the resistance caused by terrain.

The larger bar at the bottom of the page, below the Resistance Ratio label, provides the current ratio of resistance sources. The smaller bar immediately above the label provides the average ratio for the duration of your current ride.

Wind Impact widget – Map page

Wind Impact data will also appear as a fixed position widget in the upper left section of the Map page when a ride has started and the Wind layer is toggled on. It is toggled on by default. To toggle it off, select the ... using the left front button, navigate to the map layers icon (bottom left), select it, and then select the Wind layer icon.

This widget will display your current Wind Impact value in MPH or KPH to the nearest 10th. When riding into a headwind, the background of the widget will be red, and when you are supported by a tailwind or tucked into a draft, the background of the widget will be green. The widget will have a white background showing “00” if the air speed data gathered by the sensor has not passed the minimum threshold to clearly quantify a headwind or tailwind/draft benefit state.

Post Ride

After a ride, a summary of the time spent in each Wind Impact zone is visible in the ride history details on both the ACE itself and in the Wahoo app.

In the Wahoo app, the elapsed time and percentage of the ride in each Wind Impact zone (AirBoost, Neutral Air, and AirDrag) can be viewed by selecting the wind icon under the Summary panel, along with the ratio of wind to grade resistance. The same time and percentages are further broken down in the Wahoo Wind Dynamics panel below. You can also see a color coded Air speed status overlay or your completed route when you expand the map view (gray button in upper left corner) and toggle on the wind layer (button with wind icon).

Care and Maintenance

Water and dirt will reduce the accuracy of the wind sensor. If cleaning is required, gently rinse the wind sensor port with warm water at low pressure and then drain and allow to air dry. A fan or hair dryer can be used on low speed/low heat settings to accelerate the drying process.
Do NOT use any compressed air, high pressure water, or physical objects to attempt to clean the sensor port, as these may damage the waterproof membrane protecting the sensor and computer internals.

Notes

Additional accessories mounted to the handlebar may affect airflow such that wind sensor readings may be blocked or inaccurate. If you notice irregular data, please confirm that your ACE is mounted horizontally, and test without any handlebar bags, action cameras, lights, etc.
The greater the instantaneous accuracy of your bike speed data, the greater the accuracy of your wind zone data. For this reason, we recommend the use of a discrete speed sensor where possible, rather than relying on GPS speed, which is derived from GPS location over time.
The air pressure sensor can only measure the impact of the fore/aft components of wind, so either a pure headwind, tailwind, or the proportion of a cross/quartering wind that has a fore/aft impact.
Because the wind sensor is located on the front of your bicycle, it cannot measure the effectivity of changes to your physical position/orientation on the bike (tuck). What it can measure is the effectivity of your bicycle's relative position (lateral position and distance from) a rider in front of you in reducing air resistance (using your relative position to maximize your draft benefit.)

Default 4 field w/ headwind	Default 4 field w/tailwind	Full 6 field w/headwind